1. Field of the Invention
The present invention relates to a navigation system for displaying a map showing the vicinity of a user's vehicle and guiding the user along a traveling route through spoken instructions.
2. Description of the Related Art
Generally, navigation systems in vehicles determine the current position of the vehicle and read map data of the vehicle's vicinity from a data storage medium such as a CD or a DVD and then display the data on a screen. A vehicle position mark indicating the position of the vehicle is displayed on the screen. The map data of the vehicle's vicinity is scrolled during traveling of the vehicle. This allows for the vehicle position mark to always be at the center of the screen and for map information showing the vicinity of the vehicle to be understood.
Most of the latest vehicle-installed-type navigation systems are provided with a route-guiding function that enables users to travel to desired destinations without getting lost. According to this route-guiding function, the preferred (or least-cost) route between a starting position and a destination position is automatically determined using map data. This is accomplished using a simulation, such as a breadth-first search (BFS) method or Dijkstra's algorithm. The preferred route is stored as a guiding route. During driving, the screen displays the guiding route by bold lines of a different color than the colors used for the other roads. The next intersection the vehicle will approach is enlarged, and the users are guided to their destination by speech-guiding output.
Since the language used in the above-described conventional navigation system is fixed at the time of purchase, when the languages used by the user and the navigation system are different, the user may be unable to understand the contents of the displayed map and the output guiding speech. For example, when a foreigner who speaks English uses a Japanese-specification navigation system purchased in Japan, the characters contained in the map and the speech guiding are Japanese. When the user crosses borders of countries in Europe or the like when using the navigation system, the user finds it difficult to understand the contents because the map uses the local language of each country. For example, FIG. 14 shows how a synonym for the word “GERMAN” is different for each country.